1. Field of the Invention
This invention relates to disk drive devices, such as magnetic disk devices, provided with disks that rotate at high speeds and to a method of assembling the disk drive device.
2. Description of the Related Art
In general, a magnetic disk device comprises a case in which are arranged magnetic disks in the case, a spindle motor that supports and rotates the disks, a carriage assembly supporting magnetic heads, a voice coil motor for driving the carriage assembly, a substrate unit, etc.
The spindle motor has a cylindrical hub, and a plurality of magnetic disks and spacer rings are stacked on the hub. The disks and the spacer rings are held on the outer periphery of the hub by a disk clamper that is attached to the distal end of the hub.
In the magnetic disk device of this type, the rotational speed of the magnetic disks is high in order to ensure high-speed data processing. To attain this, many researches have recently been made of high-rotation magnetic disk devices. When the magnetic disks rotate at high speed, however, airflows are generated in the direction of rotation of the disks, and their disturbance or turbulence causes a phenomenon called disk flutter such that the disks vibrate. If this occurs, the accuracy of positioning of the magnetic heads with respect to the disks become worse, thus it is difficult to improve recording density.
In order to solve the above problem, a magnetic disk device with a shroud is proposed in Jpn. Pat. Appln. KOKAI Publication No. 2000-322870, for example. The shroud serves to smooth airflows in the circumferential direction of disks that are produced as the disks rotate. The shroud is in the form of a circular arc that surrounds the outer periphery of the disks. Comb-like teeth are set up on a shroud-free peripheral surface. These teeth are interposed between the disks so as to extend from the outermost periphery of the disks toward the inner periphery.
In incorporating the shroud in the magnetic disk device constructed in this manner, however, the shroud must be laterally inserted into the space between the magnetic disks. Thus, assembling the device is difficult, and its manufacturing processes are complicated.